Electromagnetic relay

ABSTRACT

An electromagnetic relay, particularly useful for telecommunications switching purposes is described. The relay has a series magnetic circuit comprised of a magnetic core encircled by an excitation winding, a short circuit yoke arranged in parallel to the winding axis of the core and two magnetizable flat armatures pivotally mounted at the front end of the short circuit yoke. The armatures are biased into a rest position by contact spring sets and thereby form two working air gaps with the poles of the magnetic core. In their operating positions the armatures magnetically bridge the short circuit yoke and the magnetic core.

United States Patent [1 1 Grassl ELECTROMAGNETIC RELAY [75] Inventor: Erwin Grassl, Munich, Germany [73] Assig'nee: Siemens Aktiengesellschaft, Berlin &

Munich, Germany [22] Filed: Mar. 8, 1972 [211 App]. No.: 232,796

[30] Foreign Application Priority Data Mar. 12, 1971 Germany 2112085 [52] U.S. Cl. 335/135, 335/265 [51] Int. Cl. H0lh 47/02 [58] Field of Search 335/135, 265, 279, 276, 335/119, 184', 267, 153

[56] References Cited I UNITED STATES PATENTS 3,184,563 5/1965 Myatt 335/153 3,633,135

111972 Stromberg et a1. 335/135 [4 1 Apr. 2, 1974 FOREIGN PATENTS OR APPLICATIONS 302,107 12/1928 Great Britain 335/265 Primary Examiner-Harold Broome 571 ABSTRACT An electromagnetic relay, particularly useful for telecommunications switching purposes is described. The relay has a series magnetic circuit comprised of a magnetic core encircled by an excitation winding, a short circuit yoke arranged in parallel to the winding axis of the core and two magnetizable flat armatures pivotally mounted at the front end of the short circuit yoke. The armatures are biased into a rest position by contact spring sets and thereby form two working air gaps with the poles of the magnetic core. in their operating positions the armatures magnetically bridge the short circuit yoke and the magnetic core.

8 Claims, 1 Drawing Figure 1 ELECTROMAGNETIC RELAY BACKGROUND OF THE lNVENTlON The invention relates to an electromagnetic relay, which is particularly useful for telecommunication systems.

Relays of this type are needed in great quantities and are often installed in a multiple arrangement, wherein the individual relays are mounted very closely to one another. Thus, it is important to reduce the production a cost of the relay to a minimum, to provide for a simple construction so as to assure a reliability and easy assembly, and finally to minimize the inductive effects to adjoining relays caused by stray fields.

Relays with comparatively simple construction are known that satisfy the requirements indicated hereinabove, and which are also suitable for automatic production and installation. However, it should be remembered that simple relay construction is obtained by using an iron circuit of low magnetic sensitivity and a simple contact arrangement. An example of the latter is that type of relay used in motor vehicles, where only a limited number of operations are required with the simplest possible contact making. By contrast, another group of relays have a highly sensitive iron circuit, as well as a simple construction suitable for automatic production, but they are equipped with contact arrangements which carry the magnetic flux, so that the number of contact arrangements of these relays is limited from the outset. The disadvantage common to these two groups of relays and other similar relays of known construction is that they have an unfavorable magnetic stray field which, although it can be compensated in a multiplearrangement, requires additional shielding elementsor a special assembly complicating the installation.

It is an object of this invention to provide a relay which avoids the disadvantages of conventional relays described hereinabove and has the simplest possible construction, which can be economically produced, which permits the provision of a large number of contact arrangements, even for complicated switching operations, and wherein the external stray magnetic field is largelyelirninated.

SUMMARY OF THE INVENTION provided, and these assume their rest positions under the influence of the contactspring sets of the relay. The

contact springs concurrently act as armature restoring springs, while forming two working air gaps with the poles of the magnet core, and in their operating position they magnetically bridge the short circuit yoke and the magnetic core under the impetus of the contact spring assemblies.

In this construction of the relay, the arrangement of two armatures and, hence, of two working magnetic air gaps provides for a decentralization and a corresponding reduction of the magnetic stray field. This arises out of the construction resulting in two working air gaps, rather than one, so that only about half the magnetic excitation is required per air gap. This naturally has a positive effect in reducing the external stray field.

According to the invention, the relay can be equipped in many ways with contact arrangements which can also be constructed as trailing contacts, in addition to the simple make contacts or break contacts. Moreover, in mixed construction arrangements the relay can also be provided with such contact sets. Also, with this division of the whole contact arrangement of the relay into individual contact groups, which can be operated by the two armatures, harmful tolerances which impair the switching reliability can be largely removed. These tolerances are well-nigh inavoidable in a construction having interdependent actuation of the individual contact springs.

Another important advantage of the invention is that the contact springs act, as well, as armature restoring springs, so that the installation of additional restoring springs can be dispensed with.

The invention results in a relay of the simplest possible construction, because, aside from the magnet core, the short-circuit yoke, the two flat armatures and the contact spring sets can be made of individual contact springs. No further components are required, and these parts can, moreover, be made with comparatively very simple implements.

Further, the objects of the invention are achieved in that the relay is constructed to have a coil frame of insulating material, preferably made in accordance with an injection molding process. The coil frame has two flanges which are mechanically and fixedly connected with one another over a winding cylinder which receives, axially, the magnetic core. Each of the flanges has an opening for receiving the short circuit yoke, and each is provided with a recess for movably receiving either of the two arrnatures on the front portions of the short circuit yoke. The coil frame is constructed to have two channels extending laterally and parallel to the longitudinal axis of the armature for seating a contact spring assembly, which projects above the movable end of the armature/At least one group of contact springs on the contact spring assemblies is constructed to operate as a reset spring for restoring the armatures to their rest positions. This coil frame, which can be made economically in one piece with all the necessary final shapings, assures easy assembly and a reliable fit with the relay parts to be installed. Due to the free accessibility to the winding cylinder,'it permits winding on modern'winding machinery prior to final assembly.

In a further development of the invention, the flanges of the coil frame, in the area of the moving end of the armatures, are provided with guide grooves, in which an insulating actuation card, which serves to indirectly actuate the contact spring sets by the armature, is slidably supported in the direction of the armature stroke. This feature of the invention permits the arrangement of at least two contact spring sets on both sides of the axial center of the armature and provides, moreover, for electric insulation of the contact springs from the armature.

If the insulation card, according to a further development of the invention, is deposited step by step into the area of engagement with the guide grooves and is given a U-shaped configuration as a whole, with the base support opposite the contact spring sets serving as the area of contact of the armature, then a precise mechanical sliding guide of the actuation card is provided. Further,- the armatures can engage in the actuation card in a space-saving method of construction.

A further development of the last-mentioned aspect of the invention provides that the armature, on its moving end, is designed as a two-pronged fork, and each flange of the coil frame in the vicinity of the guide grooves is provided with two recesses extending at right angles to the plane of the actuation card. The two prongs of the fork-shaped armature end pass through the aforesaid recesses in the flange and bear with their free ends against the base support of the actuation card. Thus, it is provided that the armature is undetachably connected at its moving end with the flange of the coil frame, and it finds a limit stop in its rest position without the need of particular mounting operations to position a stop means or the like.

According to a further development of the lastmentioned feature of the invention, the recesses in the flanges of the coil frame can be designed as sliding guides for the prongs of the fork-shaped end of the armatures. These guides can be provided for with no additional machining cost when the coil frame is made.

A further arrangement of the invention provides that on the flanges of the coil frame, at least in the area of the essentially unmoving end of the armatures and in the area of the frontal sides of the actuation cards adjoining the 'contactsets in their rest positions, conically ascending pocks are formed. These are preferably formed from the direction of insertion of the armatures or of the actuation cards viatheir leading or entering edges and dropping off substantially at right angles to the flange plane. These are undetachably held on the coil frame utilizing the elasticity of the coil frame material of inserted armatures and actuation cards. These pocks can beprovided at the time the coil frame is made, e.g., in the extrusion die, so that neither additional retaining elements as such, nor, when necessary, costly assembly operations are needed for the installation thereof.

According to a further development of the invention, the relay can be equipped with a bottom plate made fromv insulating material known as a.funnel plate. The bottom plate preferably can be locked in'po'sition by means of self-engagingsnap elements formed as interlocking recesses and projections on the coil frame. I These snap elements, aside from their known function obtained, because conventional semi-finished products can be used, and the parts themselves do not need any particular machining.

Finally, according to a further development of the invention, the armature is provided, on its stationary end, with a frontal side which extends substantially at right angles to its two longitudinal edges, as well as to its plane; two projections being provided on the comers of this area, whose vertices lie, at least approximately, in the plane formed by the aforesaid frontal side of the armature. The armature is pressed by means of a tension spring, whose mid-portion is supported under initial tension via the projections of the armature and whose ends are braced on suitable final shapings of the coil frame so as to press the same practically neutrally against the short-circuit yoke. The edge of the frontal side of the armature opposite the projections forms the pivotal axis thereof with the .pole surface of the shortas centering and holding means for the connecting elements of the relay, can function to lock the contact spring sets in position. This arrangement is based, first, on a conventional method'which has proved successful in practice for a fairly long period, i.e., to bring and maintain with the least possible effort the connecting elements of the relay for its contact springs and winding(s) in a set position. It is particularly important when construction is preformed on a grid board to stabilize and protect the assembly by mechanical means. Second,rby means of this bottom plate, the contact spring assemblies are held in their set positions without the need for additional work. Thus, in case of need, the interchangeability of individual contact springs. or whole contact spring assemblies is also maintained.

If, in accordance with a further development of the invention, the magnet core is designed as a section of a cylinder and the short-circuit yoke as a rectangular section of flat material having a suitable size and perr'neability, great price and mechanical advantages are circuit yoke. An armature can be used which can be made without cambering or other particular machining only as a punched piece from a permeable sheet metal of suitable thickness. Thus, the neutral mounting support of the armature has a particularly favorable effect on the short-circuit yoke in connection with the resetting of the armature by contact springs of the relay.

BRIEF DESCRIPTION OF THE DRAWING For a better understanding of the above described principles of the invention and others which will hereinafter appear, reference may be had to the accompanying drawing of perferred embodiments of the invention, wherein a relay is axonometrically shown in fragmentary cross-sectional view.

DETAILED DESCRIPTION OF THE DRAWING:

In the drawing, a coil frame 1 made from insulation material, preferably in accordance with the jet molding process, includes two flanges 3 and 4 having inlet and outlet slots of known construction for the connecting cables of one or more windings and a winding cylinder 2, which fixedly interconnects these two flanges by mechanical means. The winding is enclosed in the aforesaid winding cylinder 2, and therefore, not visible herein. The winding cylinder has a channel along the longitudinal axis thereof into which a magnet core 26 is pressed, so that its two ends penetrate flanges 3 and 4. 'A recess having an appropriate cross section is projections in flanges 3 and 4 parallel to the winding axis of the winding into which a rectangular short-circuit yoke 27 is permanently pressed. The yoke has frontal sides which terminate substantially in alignment with the pole ends of magnet core 26.

One of flat armatures 28 is partly visible in the drawing. These armatures 28 is partly visible in the drawing. These armatures 28 are pivotally mounted in neutral equilibrium via projections 31 formed thereon. The vertices of the porjections lie substantially on the plane formed by the closing edge of the armature. By means of spring band 29 which acts on the aforesaid projections 31, and is braced in recesses 30 of coil frame 1, the closing edge of the armature adjoining the shortcircuit yoke forms the pivot axis thereof.

A low-friction and properly positioned operating path for the armatures is ensured by means of projections 33 which are formed out of flanges 3 and 4 of coil frame 1. The moving end of the arr natures is in each case shaped like a two-pronged fork, whereby prongs 37 are guided into openings of the flanges of the coil frame. The openings are not described in detail but are clearly visible in the drawing. The free ends of the armatures abut the base support of a U-shaped actuation card 22, over which contact spring sets of the relay are actuated indirectly on both sides of the axial center of the armatures. Of these contact spring sets the two disposed on one side of the relay are identified by 7 and 8, respectively, while of the two contact spring sets on the opposite side of the relay only the contact springs of the upper contact spring set are provided with reference numerals, i.e., 9, l0, and 11. All the contact spring sets are in each case inserted into channels 5 and 6, whereby the individual contact springs are held in set positions in self-clipping fashion without any attaching means. This is attained by inserting the contact springs into grooves l2, l3 and 14 within channels 5 and 6, whereby the grooves for the unmoving contact springs penetrate the entire length of insertion up to the mov ing end 18 of these contact springs. The grooves for the moving contact springs extend only along a portion of the entire length of insertion of these contact springs, the latter having gradations l7 and 19 in adaptation thereto, so that their insertion is limited and at the same time the narrower free ends of these contact springs can move freely in the channel.

The necessary mechanical initial tension, as well as the mechanical positioning of the moving contact springs in their grooves, is effected by means of angled supporting tabs and 16, which are strutted on the inner wall of the grooves. The-mechanical mounting support of the contact spring sets on the coil frame, particularly the necessary protection from a drifting of the contact springs from their set positions, is ensured by a bottom plate '20 called a funnel plate having clearly visible stiffening ribs, not identified in the drawing. This bottom plate 20 is pushed up on the soldering lugs of the contact springs and on the connecting elements 38 of winding 2 and removably locked in position in conventional manner with coil frame 1 via snap elements not identified in the drawing.

From the particular nature of the mode of construction and assembly of the contact spring sets described hereinabove the advantage is obtained that the contact springs'can be mounted precisely without any additional fastening elements, particularly without screws, bolts or the like and without the need for special adjustment operations. Further, defective contact springs can be replaced easilyvand rapidly.

Actuation cards 22 are movably guided into two grooves 23 and 24 of the flange 3 or 4 of coil frame 1, whereby projections 25 which have been sprayed on to the flanges and which rise conically from the direction of insertion of the actuation cards and drop substantially at right angles to the flange plane, secure the inserted actuation cards undetachably in the coil frame.

Reference numeral 32 identifies the frame supports of flanges 3 and 4, which in the rest positions of armatures 28 form a stop means for the fork-shaped ends thereof. Reference numeral 34 identifies gradations on prongs 37 of the fork-shaped end of armatures 28, which are supported on the actuation card, thus, preventing the armatures from drifting. The closing edges 21 of. flanges 3 and 4 on which the moving contact springs 9 controlled directly by actuation card 22 are supported in their rest positions under initial tension, whereby the actuation cards can give way so that the armatures form a working air gap of predetermined size with the pole ends of magnet core 26. Parts 36 are ribs which are again formed out on flanges 3 and 4 of coil frame 1 and which form limiting means for actuation cards 28 in their working position, that is, when relay armature 28 is tightened. Reference numeral 35 identifies parts of the frontal side of flanges 3 and 4 pertaining to grooves 23 and 24 which contribute to an adequate sliding guide of the actuation cards.

While a description of a preferred embodiment has been given hereinabove, it is to be understood that this description is only exemplary. The scope of the invention is defined by the appended claims, and equivalents thereof, and it is anticipated that many changes or modifications in the described embodiment will fall within theseclaims.

I claim: 1. In an electromagnetic relay including a magnetic core enclosed by at least one exciting coil, short circuit yoke means arranged in parallel to the axis of said core, at least a pair of magnetically operating flat armatures in series with said magnetic core and said short circuit yoke means and contact spring means controlled mechanically by the armatures and wherein the armatures form with the magnetic core two working air gaps when the relay is not energized and actuate the contact spring means when the relay is energized, the improvement comprising:

a winding cylinder constructed to receive said magnetic core axially in the interior of said cylinder,

coil frame means constructed from insulating material and having first and second flange members fixedly connected, one to the other, over said winding cylinder means,

means defining an opening in each of said flange members for receiving said short circuit yoke means, v

means defining a recess in each of said flange members for movably seating either of said armatures on forward portions of said short circuit yoke means,

contact spring means projecting above the movable ends of said armatures with at least one portion of said contact spring means being constructed as a return spring for restoring said armatures to'their rest positions and at least a pair of channel members extending laterally and parallel to the longitudinal axis of said armatures for seating said contact spring means.

2. The electromagnetic relay defined in claim 1 further comprising:

actuation card means, constructed from insulating material, for indirectly actuating said contact spring means for said armatures and means on said coil frame for slidably supporting said actuation card so that the latter can move in the direction of the armature stroke.

3. The electromagnetic relay defined in claim 2 wherein said actuation card support means includes guide grooves for receiving said actuation cards and wherein said actuation card means are of a generally U-shaped configuration, a portion of which serves as the area of contact with said armatures.

4. The electromagnetic relay defined in claim 3 wherein the moving ends of said armatures are, respectively, formed in a generally two-pronged fork arrangement and wherein each said flange in the vicinity of said guide groove is provided'with two recesses extending at right angles to the plane of said actuation card, said prongs on said armatures passing through said recesses so as to abut the portion of said actuation card means serving as said area of contact.

5. The electromagnetic relay defined in claim 4 wherein said recesses are constructed as to form sliding guides for said prongs of said armatures.

6. The electromagnetic relay defined in claim 4 further comprising:

bottom plate means, constructed from insulating material, fastened to said coil frame for support of said relay and for locking said contact spring means into position.

7. The electromagnetic relay defined in claim 1 wherein said magnetic core is formed as a cylindrical section and said short circuit yoke is formed as a flat, rectangular section.

8. The electromagnetic relay defined in claim 1 wherein said armatures are provided at their stationary ends with a frontal side extending at right angles to the longitudinal sides of said armatures and further comprising: v

at least two projections on said armatures and tension spring means supported under initial tension by said projections, the ends of said tension spring means being supported by suitably shaped portions of said coil frame means so as to press said coil cuit yoke. 

1. In an electromagnetic relay including a magnetic core enclosed by at least one exciting coil, short circuit yoke means arranged in parallel to the axis of said core, at least a pair of magnetically operating flat armatures in series with said magnetic core and said short circuit yoke means and contact spring means controlled mechanically by the armatures and wherein the armatures form with the magnetic core two working air gaps when the relay is not energized and actuate the contact spring means when the relay is energized, the improvement comprising: a winding cylinder constructed to receive said magnetic core axially in the interior of said cylinder, coil frame means constructed from insulating material and having first and second flange members fixEdly connected, one to the other, over said winding cylinder means, means defining an opening in each of said flange members for receiving said short circuit yoke means, means defining a recess in each of said flange members for movably seating either of said armatures on forward portions of said short circuit yoke means, contact spring means projecting above the movable ends of said armatures with at least one portion of said contact spring means being constructed as a return spring for restoring said armatures to their rest positions and at least a pair of channel members extending laterally and parallel to the longitudinal axis of said armatures for seating said contact spring means.
 2. The electromagnetic relay defined in claim 1 further comprising: actuation card means, constructed from insulating material, for indirectly actuating said contact spring means for said armatures and means on said coil frame for slidably supporting said actuation card so that the latter can move in the direction of the armature stroke.
 3. The electromagnetic relay defined in claim 2 wherein said actuation card support means includes guide grooves for receiving said actuation cards and wherein said actuation card means are of a generally U-shaped configuration, a portion of which serves as the area of contact with said armatures.
 4. The electromagnetic relay defined in claim 3 wherein the moving ends of said armatures are, respectively, formed in a generally two-pronged fork arrangement and wherein each said flange in the vicinity of said guide groove is provided with two recesses extending at right angles to the plane of said actuation card, said prongs on said armatures passing through said recesses so as to abut the portion of said actuation card means serving as said area of contact.
 5. The electromagnetic relay defined in claim 4 wherein said recesses are constructed as to form sliding guides for said prongs of said armatures.
 6. The electromagnetic relay defined in claim 4 further comprising: bottom plate means, constructed from insulating material, fastened to said coil frame for support of said relay and for locking said contact spring means into position.
 7. The electromagnetic relay defined in claim 1 wherein said magnetic core is formed as a cylindrical section and said short circuit yoke is formed as a flat, rectangular section.
 8. The electromagnetic relay defined in claim 1 wherein said armatures are provided at their stationary ends with a frontal side extending at right angles to the longitudinal sides of said armatures and further comprising: at least two projections on said armatures and tension spring means supported under initial tension by said projections, the ends of said tension spring means being supported by suitably shaped portions of said coil frame means so as to press said coil frame means neutrally against said short circuit yoke means, the edges of said frontal sides of said armatures facing said projections forming the pivot axes of said armatures within the pole surface of said short circuit yoke. 